Technical Field
The present invention relates to a surveying technique.
Background Art
For example, a technique for obtaining a three-dimensional model of the topography of an object based on image data (three-dimensional topographic data in which the topography of the object is modeled as electronic data) is publicly known (for example, refer to Japanese Unexamined Patent Application Laid-Open No. 2013-96745). The image data may be obtained by photographing a civil engineering worksite or the like from the air. In this technique, work is required to add actual dimensions to the obtained three-dimensional model. In this work, reference points included in each of several tens of, to several hundreds of, or even more, still images need be found and be matched to each other among the still images.
A technique for automatically detecting the reference points by software processing has also been researched. In this technique, a step of attaching a target on a reference point is performed so as to easily detect the reference point by software processing. However, the automatic detection of the target in an image tends to yield errors, and therefore, in actual practice, an operator needs to monitor each of the still images one by one by eye and enlarge or reduce the image and identify the position of a marker in the image. This working procedure should be performed on each of several tens of, to several hundreds of, or more, still images, and this is thereby complicated and inefficient.